Laser Cylinder Machining with Feedback Correction
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Solution Overview
Problem
Existing methods for processing gravure and embossing cylinders using laser engraving face issues with incomplete evaporation of metal, leading to debris accumulation and uneven surfaces, which affect the precision of cell dimensions and depth, resulting in suboptimal printing quality.
Innovation Solution
A method and device that utilize post-processing with the laser beam to correct structural elements where deviations from target values exceed a predetermined threshold, ensuring accurate material removal and minimizing debris accumulation by measuring and adjusting the laser beam's intensity and movement to match the extent of deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam engraving is used to create cells on cylinder surface, then cell structure is formed for printing, but metal does not completely evaporate and debris accumulates in cells
Solution Approach 1:
The patent implements a feedback mechanism where an imaging device captures images of engraved cells, image processing determines actual cell parameters, and deviations from target values trigger corrective laser processing. This closed-loop control continuously monitors and corrects debris accumulation and dimensional inaccuracies, resolving the contradiction between forming precise cell structures and preventing debris buildup.
Solution Approach 2:
The patent performs preliminary imaging and measurement of cell structures immediately after initial laser engraving, before final printing operations. This allows detection and correction of debris and dimensional errors while the cylinder is still in the processing stage, preventing defective cells from reaching the printing stage and ensuring high manufacturing precision.
2Manufacturing precision
If laser beam intensity is increased to improve evaporation, then cell excavation is enhanced, but more debris is ejected from cells
Solution Approach 1:
The patent dynamically adjusts laser beam parameters based on real-time imaging feedback. The laser intensity, pulse duration, and processing speed are continuously optimized according to the measured cell dimensions and debris levels. This dynamic control allows enhanced cell excavation when needed while minimizing melt ejection by adjusting parameters to match actual processing conditions.
Solution Approach 2:
The patent changes laser processing parameters (intensity, pulse width, frequency, speed) based on feedback from cell measurements. When debris accumulation is detected, the system adjusts parameters to reduce melt ejection; when cell excavation is insufficient, parameters are modified to improve material removal while controlling debris generation.
3Manufacturing precision
If post-processing correction is applied to all cells, then manufacturing precision is improved, but processing time increases
Solution Approach 1:
The patent applies post-processing correction selectively only to cells that exhibit deviations beyond predetermined thresholds. Instead of uniformly reprocessing all cells, the system identifies specific defective cells through imaging and measurement, then applies corrective laser processing only to those locations. This localized approach maintains high manufacturing precision while minimizing additional processing time and preserving overall productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively corrects deviations in structural elements, ensuring that the final surface meets target specifications, improving printing quality by removing excess material and debris, thereby maintaining precise cell dimensions and depth, and enhancing the cleanliness of ink removal during printing.
Implementation Method 1
a part of the cylinder material adjacent to the cylinder surface evaporates at the point of impact of the laser beam due to its thermal energy
Implementation Method 2
the metal does not always evaporate completely, but only partially melts, with the resulting melt being formed by the volume expansion of the evaporating metal in the form of small metal droplets
Data Source
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AI summary
The invention relates to a process and a device (10) for machining a cylinder (12) with at least one laser beam (16), wherein recesses (22, 50) are made in a surface (20) of the cylinder using the laser beam (16) in order to produce a structure on the cylinder surface (20), wherein individual structure elements (50, 56, 62) of the structure produced are measured on at least part of the cylinder surface (20), wherein at least one geometrical measured value for each measured structure element (50, 56, 62) is compared with a corresponding geometrical desired value for the same structure element (50, 56, 62) in order to determine a difference between the measured value and the desired value, and wherein a correction is made on the basis of the differences determined. In order to make it possible to also correct irregularly occurring differences, it is proposed that, in the correction, the laser beam (16) is used to rework those structure elements (50, 56, 62) in the case of which the difference between the measured value and the desired value exceeds a predetermined extent in one direction.